Superconducting thin-film microbridges are found to have subharmonic energy-gap structure in their $I-V$ characteristics at voltages of $\frac{2\Delta }{\mathrm{Ne}}$, which on the application of microwaves develop sidebands at $\frac{2\Delta }{\mathrm{Ne}}\pm \frac{M\hslash \omega }{\mathrm{Ne}}$. The structure is explained on the basis of pair breaking by the harmonics of the Josephson radiation, both directly and via the normal electrons. An enhancement of the energy gap apparently induced by the Josephson radiation is observed in the subharmonic structure.

The scaling hypothesis for a tricritical point has not received any tests from experimental data for magnetic systems. Here, data for dysprosium aluminum garnet are used to test the tricritical scaling hypothesis in the directions ${\overline{x}}_2$, ${\overline{x}}_3$ lying in the $H-T$ plane. Specifically, $M-H-T$ data near the tricritical point are found to collapse from a family of curves to a single curve (scaling function), supporting the validity of a tricritical scaling hypothesis.

A theoretical study, for the first time, of the electric field gradient in cadmium metal at two pressures yields a pressure variation in agreement with time-differential perturbed-angular-correlation data. The sign of the net electric field gradient determined by the electronic contribution, which is larger and of opposite sign to the ionic contribution, in conjunction with imminently expected experimental sign of the coupling constant, will provide the sign of the excited ${\mathrm{Cd}}^{111}$ quadrupole moment.

We consider the surfaces of the condensed phase of excitons in semiconductors, the electron-hole liquid (EHL). By using the theory of the inhomogeneous electron gas and a variational technique we estimate the surface tension for the EHL in Ge to be ${10}^{-4\mathrm{}}$ erg/${\mathrm{cm}}^2$; the carrier density in the surface region varies on a scale of ≈ 50 Å. We suggest an experiment to measure the surface tension of the EHL.

We report experimental evidence for a strong spin-orbit effect on the Si valence band. A theoretical evaluation of this effect on the hole mobility in the range of temperatures between 12 and 200°K is consistent with band-structure calculations, cyclotron-resonance measurements, and transport properties.

Calculated low-energy electron diffraction spectra for $c(2\mathrm{}\times 2)$ overlayer structures of O, S, Se, and Te on Ni(001) show very good agreement with experiment for fourfold coordinated bonding sites and displacements of 0.90, 1.30, 1.45, and 1.90 ± 0.1 Å, respectively, from the center of the first layer of nickel atoms. These adsorbate-atom locations correspond to Ni-chalcogen bond lengths smaller than occur in bulk compounds, but comparable to those found in divalent Ni-chelate complexes.

Experimental results suggest that (1) switching in thin chalcogenide glass films is fundamentally electronic, and (2) the regime of pure electronic initiation has been exposed.

The properties of a particular Van Hove singularity in the electron energy bands of iron have been studied theoretically. Its presence in iron bands may explain the anomaly in the isomer shift of iron near $T_c$ discovered by Preston, Hanna, and Heberle some time ago. To date, no satisfactory theory has been given for this anomaly. The explanation offered here uses a newly calculated conduction-electron density of states and depends on a small (∼10 mRy) band shift. In addition, the effects of the singularity on other electronic properties of iron are discussed.

We have studied the interface between regions of opposite spin in the simple cubic Ising model. Low-temperature expansions of moments of the gradient of the density profile and of the slope at its midpoint suggest that the interface width diverges at a temperature $T_R$ about half the critical temperature. We discuss the physical significance of this transition and implications for general theories of interfacial properties.

We have made a high-resolution study of the weak transitions in the reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}(d, p){}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$. $J^{\pi }$ assignments are suggested for several states on the basis of new $l=2, 3, 4, 5, \mathrm{and} 6$ determinations. It is suggested that the known 2010- and 2462-keV states form band heads of $K={\frac{3}{2}}^{+} \mathrm{and} {\frac{3}{2}}^{-}$ rotational bands, respectively. The members of the $K={\frac{3}{2}}^{+}$ band are the states 2010 keV, ${\frac{3}{2}}^{+}$; 2605 keV, ${\frac{5}{2}}^{+}$; 2882 keV, ${\frac{7}{2}}^{+}$; 3201 keV, ${\frac{9}{2}}^{+}$; and 3678 keV, ${\frac{11}{2}}^{+}$. The members of the $K={\frac{3}{2}}^{-}$ band are the states 2462 keV, ${\frac{3}{2}}^{-}$; 2575 keV, ${\frac{5}{2}}^{-}$; 2960 keV, ${\frac{7}{2}}^{-}$; 3370 keV, ${\frac{9}{2}}^{-}$; and 3831 keV, ${\frac{11}{2}}^{-}$. Parallel rotational bands in the mirror nucleus ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ are also suggested.

A nonlocal energy-dependent imaginary optical potential for $s$-wave neutrons incident on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ is calculated in the intermediate structure model with particle-vibration coupling. The energy dependence is studied in the range of 0-12 MeV. The absorption cross section is calculated and compared to experiment below 2.6 MeV, the inelastic threshold. The agreement is quite good. The radial dependence is also investigated.

Discrepancies between observed ratios of $d$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and $d$, $t$ yields populating analog states in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ and ratios calculated by standard distorted-wave theory, which were thought to provide evidence for a charge-dependent nuclear interaction, are resolved by extending the conventional theory to include both an explicit charge-exchange channel in the continuum and foŕm factors generated from a microscopic analysis.

We have observed the decay mode $f^0\to {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^{-}$ and determined the branching ratio $\frac{\Gamma (f^0\to {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^{-})}{\Gamma (f^0\to {\pi }^{+}{\pi }^{-})}=(5.5\mathrm{}\pm 1.0)\times {10}^{-2\mathrm{}}$.

We report the results of an initial investigation of high-energy neutrino interactions using a dichromatic neutrino beam. Two bands of neutrinos, from pion decay ($〈E_{\nu }〉\approx 50$ GeV) and kaon decay ($〈E_{\nu }〉\approx 145$ GeV), were incident on a counter-spark-chamber detector. We discuss analysis of events of the type ${\nu }_{\mu }+N\to {\mu }^{-}+\mathrm{hadrons}$. Qualitative comparisons are made with lower-energy neutrino results and the deep-inelastic $e-N$ scaling structure functions.

In a combined analysis of low-energy nucleon-nucleon and hyperon-nucleon scattering we have determined some of the parameters of the scalar-meson nonet. We find that the $\epsilon$ meson is dominantly a unitary singlet. Simultaneously, we obtain good values for the $\frac{F}{\mathrm{}(F+D)\mathrm{}}$ ratios and coupling constants for the pseudoscalar and vector mesons.

The photodetachment cross section of ${\mathrm{I}}^{-}$ has been measured from threshold to about 1950 Å. Of particular interest is an apparent resonance in the cross section at approximately 2250 Å, which is attributed to an autodetaching state of the negative ion.

From a detailed analysis of the Mössbauer quadrupole spectra of ${\mathrm{S}\mathrm{b}\left(\mathrm{C}{\mathrm{H}}_3\right)}_3$${\mathrm{Br}}_2$ measured using the 37.15-keV $\gamma$ ray of ${}_{}{}^{121}{}_{}{}^{}\mathrm{Sb}$, it is shown that the large Goldanskii-Karyagin effect reported in this compound is not conclusive; the spectra are well accounted for by a transmission integral to include the absorber-thickness effects. Such an analysis also yields an $e^2{q}_{z}Q$ in agreement with nuclear-quadrupole-resonance measurements.

Near-resonant light pulses were steepened by passage through Rb vapor. The rise time changed from typically 4 nsec to less than 1 nsec, and complicated envelopes developed. The self-steepening, well described by adiabatic following, results from (i) an intensity-dependent pulse velocity, (ii) self-phase modulation combined with strong groupvelocity dispersion. Numerical integration gives quantitative agreement with observations and indicates shock formation on the leading edge.

Energy-distribution measurements are presented for the hot nonthermal-electron tail produced by anomalous microwave absorption near the plasma frequency ${\omega }_p$. These distributions depend strongly on $\frac{{{\omega }_p}^2}{{\omega }^2}$ and microwave power. In some cases a large fraction of the anomalously absorbed power goes into less than 1% of the electrons and a bump develops on the hot tail.

A laser plasma, expanding through a photoionized background plasma under collisionless conditions, experiences a significant coupling with the background when an external 700-G field is applied transverse to the flow. A density maximum is formed which decelerates according to the predictions of a conserved-momentum coupling model. The results are consistent with theoretical treatments of magnetized two-stream instabilities.